> we have social mechanisms for dealing with mistrust in place since forever ... People know how to deal with those situations effectively between themselves.

> we have social mechanisms for dealing with mistrust in place since forever ... People know how to deal with those situations effectively between themselves. As some of the other commenters have mentioned, the problem seems to be that these social mechanisms don't scale. Please take my point 2) in combination with point 3). As I said, techies are the exception, not the rule. It's not just Grandma who will have trouble with a web of trust, it's pretty much everyone except us. How do they even know which peers to distrust? Will there be a news feed about compromised peers? Will everyone have to subscribe to one? What if someone wants to explore a part of the web that none of their peers, or their peers' peers, have ever heard about? The single most important advantage of a centralized model of trust is that a list of trustworthy vs. untrustworthy parties can be quickly and widely distributed in an automated fashion. Comodo issues phony certs? 12 hours later, every copy of Firefox receives an updated list of revoked keys. I know it doesn't currently work like that, but it's entirely possible. Whereas with a web of trust, millions of people will be left trusting compromised peers for many months afterward because they didn't get the news.